1. Field of the Invention
This invention relates to sewing machines in general and more paricularly to sewing machines having needle thread tension adjusting devices.
2. Description of the Prior Art
Needle thread tension adjusting devices are well known in the prior art. See for example U.S. Pat. No. 2,955,775 to Johnson; U.S. Pat. No. 2,965,058 to Herbst et al; U.S. Pat. No. 3,667,414 to Illes et al; and U.S. Pat. No. 3,785,309 to Ketterer. Each of the cited patents discloses a needle thread tension adjusting device which employs a form of circular dial for setting the tension thereof. One problem associated with prior known needle thread tension adjusting devices is the number of components required to assemble the device. Another problem is the difficulty encountered in initially adjusting the devices when they are assembled so that the same tension setting on successive devices produces the identical needle thread tension.